Biceps femoris and semitendinosus—teammates or competitors?
The predominant mechanism for hamstring injury in football occurs during acceleration or high-speed running. Both the semitendinosus (ST) and biceps femoris (BF) engage in maximal eccentric activation during the swing phase of running. However, both muscles activate alternatingly in a complex neuromuscular coordination pattern, with the BF predominantly activated during middle-to-late swing, whilst the ST is the leading player in terminal swing. The following study assessed how the different hamstring muscle bellies work together synergistically, and whether changes in coordination are associated with injury.
A more symmetrical muscle recruitment pattern corresponding to a less economic hamstring muscle activation was observed amongst 27 football players with a history of hamstring injuries; compared with 27 healthy controls. Furthermore, the study group possessed a significantly lower strength endurance capacity.
These findings demonstrate discrete differences in neuromuscular coordination and activity distribution between the BF and ST in previously injured hamstrings, which may increase the risk of hamstring injury in the future.
> From: Schuermans et al., Br J Sports Med Epub ahead of print (2014) (Epub ahead of print). All rights reserved to . Click here for the Pubmed summary.